Patent GB-606975-A (GB)
Title: Improvements in tubular, natural circulation steam generators
IPC: F22B21/34
Filed: 1945-11-22
Abstract: 606,975. Water-tube steam boilers; heating air; feedwater heating systems. BABCOCK & WILCOX, Ltd. Nov. 22, 1945, No. 31515. Convention date, Nov. 29, 1944. [Classes 64(i), 64(iii) and 123(ii)] A transportable steam boiler, adapted to operate as part of a mobile power plant, comprises an upper steam and water drum 50 and lower water headers 26, 28, 30, a combustion chamber 40 having fuel burners 131, 133 in its front wall and lined with banks 55-60 of radiant-heat steam-generating tubes connecting the drum 50 to the side headers 26, 30, further banks of convection-heated steam-generating tubes 44-48 in an extension of the chamber 40 and connecting the drum 50 to all three lower headers, and downcomers 80-96 between said drum and headers. A super-heater 171, an economizer 218 disposed at the rear of the boiler, and air heaters 100, 101, located between the burners 131, 133 and air inlets 130, 132, are also provided. The side headers 26, 30 extend the full length of the drum 50 and are divided by diaphragms 250, 252 into fore and rear compartments for association respectively with the radiation and convection sections of the boiler, whereas the intermediate header 28, which is connected to the side headers by equalizing tubes 258, 260, 262-265, is of less length and is associated with the convection section only. All the downcomers are protected from the direct heat of the furnace, the groups 80-83 by a refractory wall 122, 126, the group 84-87 by the superheater 171 and tube banks 44 45, and the three groups 88-96 by providing the surrounding water tubes, which define a rectangular enclosure, with wing studs 235, Fig. 16, extending from diametrically opposite sides thereof. The air heaters 100, 101 are also downcomers, each being constituted by a bank of small-diameter finned tubes which are connected at their lower ends to the header 26 or 30 and extend upwardly to one of two headers 104 connected to the water space of the drum 50, in front of an end wall 120 of a steam and water inlet chamber 62 within the latter, by large pipes 106, 108, 110. The chamber 62 of the drum 50, into which all the steam generating tubes and downcomers open, is defined by a diaphragm 64 extending from one side of the drum and provided with end closures 120, 121, the other side of the diaphragm having an upright wall 66 to which are secured whirl units 68 for centrifugally separating steam and water from the incoming mixture admitted thereto through openings in the said wall 66. The outlets 72 from the units 68 lead through multiple plate separators 74 into the steam space 76 of the drum. The superheater 171 comprises pested U-tubes which are supported from the downcomers 86, 87 by vertical plates 180. 182 and extend between headers 190, 170, steam being supplied to a lower compartment 191 of the header 190 by pipes 160-163, the upper ends 141-144 of which are connected to the steam space of the drum 50, and then passing successively through the superheater tube banks 174, 176, header 170, tube banks 184, 186, pipe 189, to main and auxiliary steam outlets 194, 195. The economizer 218 is disposed rearwardly of the generating tube bank 48 and includes a header divided by a diaphragm 272 into inlet and outlet compartments 220, and 224, an intermediate header 222, and flat coils of return bend tubes 216 between the said headers. Inspection or replacement of the economizer elements is facilitated by the provision of detachable gas-tight panels 212, 214 in the boiler casing. The boiler is designed for permanent mounting on a railway truck, Fig. 15, which comprises a structure having upper and lower side chords 19, 21, diagonals such as 23, 25 and 27, end and intermediate uprights 150, 151 and 153, 155 respectively, and base wheels 330, 331, the drum 50 being supported fixedly at its front end by upper and lower parts 402, 404 of the web of a transverse beam 157 extending between the uprights 150 and freely at its other end, to permit expansion, by a beam 159 extending between the uprights 151. The front ends of the headers 26, 30 and the rear end of the header 28 are anchored to transverse members, not shown, at the base of the truck, said anchoring means preventing side sway of the headers but permitting movement thereof due to expansion and contraction of the steam generating tubes. Specification 559,696 is referred to.